Process for Preparing Optically Active Aminopentane Derivative, Intermediate and Process for Preparing Intermediate

ABSTRACT

There are provided a process for preparing an optically active aminopentane derivative that is promising as a psychotropic agent, an antidepressant agent, an antiparkinsonian agent, an anti-Alzheimer&#39;s agent, an apoptosis inhibitor, or the like; a novel optically active intermediate oxathiazolidine derivative very useful in the production of the aminopentane derivative; and process for the production thereof. 
     The optically active aminopentane derivatives can be produced in an industrially advantageous manner from a novel optically active oxathiazolidine derivative represented by formula (5): 
     
       
         
         
             
             
         
       
     
     wherein * indicates the position of an asymmetric carbon atom in the R or S configuration, and n is 0 or 1.

TECHNICAL FIELD

The invention relates to a process for preparing an optically activeaminopentane derivative that is promising as a psychotropic agent, anantidepressant agent, an antiparkinsonian agent, an anti-Alzheimer'sagent, an apoptosis inhibitor, or the like. The invention also relatesto a novel intermediate for preparing the aminopentane derivative and aprocess for preparing the intermediate.

BACKGROUND ART

A particular class of aminopentane derivatives have already beendescribed as having a catecholaminergic activity enhancing effect (CAEeffect) by enhancing membrane potential dependent exocytosis, whicheffect differs from that of monoamine oxidase inhibitors, catecholamineuptake inhibitors or catecholamine substitution type release stimulatingagents (for example, see Patent Literature 1 listed below). Inparticular they have been described to be devoid of excessivecatecholamine release or amine depletion at catecholamine nerveterminals, which are observed with catecholamine substitution typerelease stimulating agents.

Such aminopentane derivatives are expected to have fewer side effectssuch as abnormal hyperactivity (excitatory effect) and neurotoxicity inthe central nervous system, to have fewer problems such as decreasingresponsiveness of patients, and to be highly effective as a safe anduseful antidepressant, psychotropic, antiparkinsonian, oranti-Alzheimer's agents. It has also been reported that the aminopentanederivatives have an asymmetric carbon in the molecular structure andoptically active isomers of them were found to be more effective thanracemates (for example, see Patent Literature 2 and Non-PatentLiterature 1 listed below).

Concerning 1-(benzofuran-2-yl)-2-propylaminopentane, for example, the(−) form with the R configuration has a higher pharmacological activityas compared with the (+) form with the S configuration or the racemate(see Patent Literature 2 and Non-Patent Literature 1). In addition, itis disclosed that the (R)-1-(benzofuran-2-yl)-2-propylaminopentane hasan anti-apoptosis activity and is potentially useful as an apoptosisinhibitor against Alzheimer's disease, Parkinson's disease, Huntington'sdisease, amyotrophic lateral sclerosis, retinitis pigmentosa, glaucoma,nervous diseases such as spinocerebellar degeneration, ischemic braindiseases such as stroke, neurodegenerative diseases such as peripheralnerve disorder observed in diabetes, AIDS, and toxic diseases (forexample, see Patent Literature 3 listed below).

Conventionally known process for preparing optically active aminopentanederivatives such as (R)-1-(benzofuran-2-yl)-2-propylaminopentanecomprises a synthesis of the racemates from various aromatic aldehydesvia nitroalkene intermediates followed by their optical resolution.However, such processes require not only an equivalent amount or more ofa reagent, such as an optically active acid, to the amine but alsotroublesome operation such as crystallization, separation andpurification. For example, optically active(R)-1-(benzofuran-2-yl)-2-propylaminopentane could not be obtained froma synthesized racemate by an optical resolution via formation ofdiastereomeric salts or derivatives but could only be separated bypreparative high-performance liquid chromatography using a chiralcolumn. Such separation requires a large amount of solvent and a lot oftime and is a less productive method by which only at most about 50% ofthe desired optically active substance can be recovered (see PatentLiteratures 1 and 2). Other methods using enzymes and some asymmetricsynthesis methods are also known and they might be applicable to apreparation of the aminopentanes, however, these methods are lesspractical in view of limited substrates, insufficient selectivity andcomplicated operation.

Thus, there have been developed two different practical processes forpreparing optically active 1-(benzofuran-2-yl)-2-propylaminopentane. Thefirst process comprises treating an optically active aziridinederivative prepared from an optically active norvaline with 2-benzofuranlithium to build up a framework of the optically active1-(benzofuran-2-yl)-2-propylaminopentane. The second process comprisestreating an optically active N-methoxy-N-methylamide derivative preparedfrom an optically active norvaline with 2-benzofuran lithium to obtain aketone and reducing the ketone to build up a framework of the opticallyactive 1-(benzofuran-2-yl)-2-propylaminopentane. The development ofthese two processes allows efficient production of both optically activeisomers of 1-(benzofuran-2-yl)-2-propylaminopentane (see PatentLiterature 4 listed below). However, research and development has beencarried out in order to seek more industrially advantageous processesthan these processes.

Patent Literature 1: Pamphlet of International Publication No.WO99/07667

Patent Literature 2: Japanese Patent Application Laid-Open (JP-A) No.2000-136187

Patent Literature 3: JP-A No. 2003-89643

Patent Literature 4: Pamphlet of International Publication No.WO01/77074

Non-Patent Literature 1: Yoneda et al., Bioorganic & MedicinalChemistry, 2001 Vol. 9, pp. 1197-1212

DISCLOSURE OF THE INVENTION Objects of the Invention

It is an object of the invention to provide a novel process forpreparing an optically active aminopentane derivative useful as apsychotropic agent, an antidepressant agent, an antiparkinsonian agent,an anti-Alzheimer's agent, an apoptosis inhibitor, or the like, toprovide a novel intermediate for preparing the optically activeaminopentane derivative, and to provide a process for preparing theintermediate.

Means for Solving the Problems

As a result of intensive investigations, the inventors have found anovel optically active oxathiazolidine derivative represented by formula(5):

wherein * indicates the position of an asymmetric carbon atom in the Ror S configuration, and n represents 0 or 1,is a very useful intermediate, which can be prepared from a commerciallyavailable optically active norvaline, in the production of the opticallyactive aminopentane derivative.

The inventors have also found a novel process for preparing an opticallyactive aminopentane derivative via the above novel intermediate.

Specifically, the inventors have found that the optically activepropylaminopentane derivative represented by formula (8):

wherein Ar represents an aryl group and * indicates the position of anasymmetric carbon atom in the R or S configuration, can be easilyprepared in high selectivity and good yield by the following steps:treating an optically active oxathiazolidine derivative represented byformula (5-1):

wherein * has the same meaning as defined above, with an oxidizing agentin the presence of a ruthenium catalyst to obtain an optically activeoxathiazolidine derivative represented by formula (5-2):

wherein * has the same meaning as defined above;

treating the oxathiazolidine derivative with an aryl lithium representedby formula (6):

Ar—Li  (6)

wherein Ar has the same meaning as defined above to obtain an opticallyactive lithium N-sulfonate derivative represented by formula (7):

wherein Ar and * each has the same meaning as defined above; and

hydrolyzing the above lithium N-sulfonate with an acid to obtain anoptically active propylaminopentane derivative represented by formula(8):

wherein Ar and * each has the same meaning as defined above. Thus, theinvention has been completed.

The optically active oxathiazolidine derivative represented by formula(5) as a novel intermediates comprise the compounds represented byformulae (5-1) and (5-2), and can be prepared by the process describedbelow.

i) Esterification of an optically active norvaline represented byformula (1):

wherein * has the same meaning as defined above,with an alcohol pretreated with thionyl chloride to give an opticallyactive norvaline ester derivative represented by formula (2):

wherein R represents a lower alkyl group, and * has the same meaning asdefined above. In this step, for example, the alcohol may be a lower C₁to C₆ alcohol such as methanol, ethanol or propanol, preferably a lowerC₁ to C₃ alcohol. This reaction may be performed under conventionalconditions for esterification using thionyl chloride and alcohols.

ii) Amidation of the above ester derivative with propionic anhydride inthe presence of a base and in a solvent to give an optically activeN-propionylnorvaline ester derivative represented by formula (3):

wherein R and * each has the same meaning as defined above. In thisstep, for example, the solvent may be water or a combination of waterand an organic solvent such as dichloromethane or ethyl acetate. Thebase may be an inorganic base such as sodium hydrogen carbonate, sodiumcarbonate, potassium hydrogen carbonate, or potassium carbonate, or anorganic base such as triethylamine, pyridine or N-methylmorpholine. Thereaction temperature is generally from 0 to 40° C., preferably from 15to 20° C., and the reaction time is generally from 30 minutes to 1 day,preferably from 1 to 3 hours.

iii) Reduction of the carboxyl group and the amide group in the aboveamide derivative with a reducing agent in a solvent to give an opticallyactive N-propylnorvalinol represented by formula (4):

wherein * has the same meaning as defined above. In this step, forexample, the reaction solvent may be an organic solvent such astetrahydrofuran, diethyl ether, and diisopropyl ether. The reducingagent may be a known reducing agent such as lithium aluminum hydride.The reaction temperature is generally from 20 to 120° C., preferablyfrom 35 to 70° C., and the reaction time is generally from 2 hours to 1day, preferably from 2 to 4 hours.

iv) Formation of a 1,2,3-oxathiazolidine ring from the abovepropylnorvalinol using thionyl chloride in the presence of a base and ina solvent to give an optically active oxathiazolidine derivativerepresented by formula (5-1):

wherein * has the same meaning as defined above. In this step, forexample, the solvent may be an organic solvent such as dichloromethane,1,2-dichloroethane, ethyl acetate, toluene, acetonitrile,tetrahydrofuran, N,N-dimethylformamide, acetone, or hexane. For example,the base may be an organic base such as triethylamine, imidazole,N-methylmorpholine, pyridine, or N,N-diisopropylethylamine. The reactiontemperature is generally from −20 to 60° C., preferably from −15 to 30°C., and the reaction time is generally from 30 minutes to 1 day,preferably from 3 to 4 hours.

v) Oxidation of the above oxathiazolidine derivative with an oxidizingagent in the presence of a ruthenium catalyst and in a solvent to givean optically active oxathiazolidine derivative represented by formula(5-2):

wherein * has the same meaning as defined above. In this step, forexample, the solvent may be a mixture of water and an organic solventsuch as ethyl acetate, acetonitrile, diisopropyl ether, dichloromethane,or 1,2-dichloroethane, or a mixture of a buffer solution such as aphosphate buffer solution and an organic solvent such as ethyl acetate,acetonitrile, diisopropyl ether, dichloromethane, or 1,2-dichloroethane.For example, the ruthenium catalyst may be ruthenium trichloride,ruthenium dioxide or the like. For example, the oxidizing agent may besodium periodate, an aqueous sodium hypochlorite solution, or the like.The reaction temperature is generally from 0 to 40° C., and the reactiontime is generally from about 1 to 3 hours.3,4-Dipropyl-1,2,3-oxathiazolidine 2-oxide, which is an optically activeoxathiazolidine derivative of formula (5-1), has additional chiralcenter at the sulfur atom and thus may be a mixture of diastereoisomers,in which the component ratio may depend on the reaction conditions inthe above step iv). Regardless of the ratio of diastereoisomers,however, 3,4-dipropyl-1,2,3-oxathiazolidine 2,2-dioxide, which is anoptically active oxathiazolidine derivative of formula (5-2), can beobtained in the step v). From the novel optically active oxathiazolidinederivative of formula (5) thus obtained, the desired optically activeaminopentane derivative can be prepared by the process described below.

vi) Ring opening reaction of the above oxathiazolidine derivative offormula (5-2) with an aryl lithium represented by formula (6) in asolvent to give an optically active lithium N-sulfonate derivativerepresented by formula (7):

wherein Ar and * each has the same meaning as defined above. Forexample, the aryl group represented by Ar may be phenyl, thienyl,naphthyl, benzofuryl, benzothienyl, methylenedioxyphenyl, or indolyl.The aryl group may have a substituent(s) such as C₁ to C₃ alkyl on itsaromatic ring, if it does not obstruct the reaction. The aryl lithiummay be prepared by treating a corresponding aromatic compound withn-butyl lithium. The step vi) is be performed in an appropriate solvent.For example, such a solvent may be an organic solvent such astetrahydrofuran or diethyl ether. In this step, if desired, an additivesuch as N,N,N′,N′-tetramethylethylenediamine or 1,2-dimethoxyethane maybe added as appropriate. The sulfonate derivative can be obtained as areaction mixture or can be obtained as an aqueous solution byliquid-liquid separation after water is added to the reaction mixture.The reaction is preferably performed under an inert atmosphere (nitrogenor argon, preferably nitrogen). The reaction temperature is generallyfrom −10 to 10° C., and the reaction time is generally from 1 to 4hours.

vii) Hydrolysis of the above sulfonate derivative in the reactionmixture or in the aqueous solution thereof with an acid to give anoptically active aminopentane derivative represented by formula (8):

wherein Ar and * each has the same meaning as defined above. In thisstep, for example, the acid may be hydrochloric acid, sulfuric acid,hydrobromic acid, or the like. The reaction temperature is generallyfrom 0 to 40° C., and the reaction time is generally from about 1 hourto about 1 day.

The resulting aminopentane derivative may be converted into apharmacologically acceptable acid addition salt thereof, which includesan inorganic acid such as hydrochloric acid, sulfuric acid, hydrobromicacid, nitric acid, or methanesulfonic acid, or a salt of an organic acidsuch as gluconic acid, tartaric acid, maleic acid, fumaric acid,succinic acid, malic acid, citric acid, or mandelic acid.

There is no particular limitation on the reaction temperature and thereaction time in each step described above, however, they are preferablywithin the range of the conventional conditions in each step in view ofthe properties of the reaction reagents.

EFFECTS OF THE INVENTION

The use of the novel optically active oxathiazolidine derivativerepresented by formula (5) as a production intermediate facilitates theefficient production of both optically active aminopentane derivativeisomers with high purity and establishes industrially advantageousprocess for preparing optically active aminopentane derivatives.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is described in more detail with reference to thefollowing examples which are not intended to limit the scope of theinvention.

EXAMPLES Example 1 Synthesis of (R)-Norvaline Methyl Ester

Thionyl chloride (47.7 mL) was added dropwise to methanol (300 mL) understirring at −5° C. over 2 hours and 15 minutes. D-Norvaline (35.00 g)was added to the resulting light yellow solution under stirring at −4°C. The solution was stirred at room temperature for 18 hours and thenmethanol was removed under reduced pressure. Disopropyl ether (90 mL)was added to the precipitated crystals, which were filtered and washedtwice with diisopropyl ether (30 mL) to give (R)-norvaline methyl ester(47.74 g, 95% yield) as a white powder.

Melting point: 109-110° C.

MS (m/z) 132, 88, 72

IR (KBr) 3440, 2970, 1753, 1585, 1502, 1443, 1382, 1283, 1243, 1165,1123, 1032, 994, 937, 898, 740 cm⁻¹

NMR (CDCl₃) δ 0.97 (t, 3H, J=7.4 Hz), 1.38-1.75 (m, 2H), 2.05 (q, 2H,J=7.4 Hz), 3.82 (s, 3H), 4.18 (t, 1H, J=6.4 Hz), 8.45-9.15 (br, 3H) ppm

Specific rotation: [α]_(D) ²⁰−20.51° (CHCl₃, c=1.056)

Example 2 Synthesis of (S)-Norvaline Methyl Ester

(S)—Norvaline methyl ester (18.2 g, 100% yield) was obtained as acolorless crystals, following the procedure of Example 1, but usingL-norvaline (12.7 g) and thionyl chloride (17.3 mL).

Example 3 Synthesis of (R)—N-Propionylnorvaline Methyl Ester

(R)—Norvaline methyl ester (30.35 g) was added to an aqueous solution(180 mL) of sodium hydrogen carbonate (15.21 g) under ice-cooling andstirring and then stirred for 5 minutes under ice-cooling. Propionicanhydride (25.5 mL) and sodium hydrogen carbonate (8.36 g) were slowlyand alternately added to the resulting solution and stirred for 1 hourunder ice-cooling. The resulting two-layer solution was extracted withethyl acetate (90 mL). The organic layer was washed with a saturatedaqueous sodium hydrogen carbonate solution (50 mL), dried over anhydroussodium sulfate and then concentrated under reduced pressure to give(R)—N-propionylnorvaline methyl ester (33.79 g, 99% yield) as a paleyellow oil.

IR (KBr) 3295, 3060, 2955, 2870, 1742, 1651, 1540, 1460, 1440, 1378,1206, 1157, 1068, 1020 cm⁻¹

NMR (CDCl₃) δ 0.93 (t, 3H, J=7.4 Hz), 1.17 (t, 3H, J=7.7 Hz), 1.23-1.48(m, 2H), 1.56-1.72 (m, 1H), 1.74-1.89 (m, 1H), 2.26 (q, 2H, J=7.7 Hz),3.74 (s, 3H), 4.63 (dt, 1H, J=5.4, 7.4 Hz), 5.87-6.20 (br, 1H) ppm

Specific rotation: [α]_(D) ²⁰−20.91° (CHCl₃, c=1.006)

Example 4 Synthesis of (S)—N-Propionylnorvaline Methyl Ester

(S)—N-Propionylnorvaline methyl ester (20.7 g, 100% yield) was obtainedas a slightly yellowish oil, following the procedure of Example 3, butusing (S)-norvaline methyl ester (18.2 g) and propionic anhydride (14.9g). NMR (CDCl₃) δ 0.93 (t, 3H, J=7.4 Hz), 1.17 (t, 3H, J=7.4 Hz),1.23-1.50 (m, 2H), 1.50-1.72 (m, 1H), 1.72-1.90 (m, 1H), 2.26 (q, 2H,J=7.4 Hz), 3.74 (s, 3H), 4.51-4.75 (m, 1H), 5.87-6.20 (br, 1H) ppm

Example 5 Synthesis of (R)—N-Propylnorvalinol

Lithium aluminum hydride (5.47 g) was added to tetrahydrofuran (144 mL)with stirring at 4° C. and then stirred under ice-cooling for 15minutes. A solution of (R)—N-propionylnorvaline methyl ester (15.87 g)in tetrahydrofuran (85 mL) was added dropwise to the resultingsuspension over 70 minutes under stirring at 4° C. and then stirred for15 minutes under ice-cooling. The suspension was refluxed and stirredfor 2 hours and then stirred under ice-cooling for 20 minutes, and anaqueous solution (25 mL) of 1 mol/L sodium hydroxide was added dropwisethereto over 12 minutes and stirred under ice-cooling for 5 minutes. Thesuspension was refluxed and stirred for 1 hour. The suspension wasfiltered and washed with ethyl acetate (23 mL). The insoluble matter wassubsequently washed twice with hot ethyl acetate (115 mL). The filtrateand the washings were combined and dried over anhydrous sodium sulfatefor 12 hours and then concentrated under reduced pressure to give(R)—N-propylnorvalinol (11.97 g, 97% yield) as a yellow oil.

MS (m/z) 144, 114, 86, 72

IR (KBr) 3300, 2960, 2940, 2875, 1650, 1464, 1386, 1247, 1150, 1057, 902cm⁻¹

NMR (CDCl₃) δ 0.93 (t, 6H, J=7.4 Hz), 1.20-1.64 (m, 6H), 2.44-2.73 (m,3H), 3.25 (dd, 1H, J=6.7, 10.4 Hz), 3.60 (dd, 1H, J=4.0, 10.4 Hz) ppm

Specific rotation: [α]_(D) ²⁰−36.47° (CHCl₃, c=1.074)

Example 6 Synthesis of (S)—N-Propylnorvalinol

(S)—N-Propylnorvalinol (15.5 g, 96% yield) was obtained as a colorlessoil, following the procedure of Example 5, but using(S)—N-propionylnorvaline methyl ester (20.7 g) and lithium aluminumhydride (8.37 g).

NMR (CDCl₃) δ 0.93 (t, 6H, J=7.0 Hz), 1.23-1.68 (m, 6H), 2.46-2.76 (m,3H), 3.28 (dd, 1H, J=6.3, 10.4 Hz), 3.60 (dd, 1H, J=4.0, 10.7 Hz) ppm

Example 7 Synthesis of (R)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide

(R)—N-Propylnorvalinol (11.53 g) was dissolved in dichloromethane (160mL), and N-methylmorpholine (21.8 mL) was added thereto under stirringat room temperature. A solution of thionyl chloride (6.9 mL) indichloromethane (48 mL) was added dropwise to the resulting solutionover 120 minutes under stirring at 2° C. The resulting suspension wasstirred at room temperature for 4 hours. Water (104 mL) was added to thesuspension under stirring at 3° C. The mixture was separated and theorganic layer was washed with an aqueous 1 mol/L hydrochloric acidsolution (104 mL) and subsequently with a saturated aqueous sodiumhydrogen carbonate solution (104 mL), dried over anhydrous magnesiumsulfate and then concentrated under reduced pressure. The residue wasdried under reduced pressure at room temperature for 19 hours to give(R)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide as a red oil (12.36 g,81% yield, cis:trans=about 45:55 determined from the integration ratioin ¹H-NMR).

MS (m/z) 190, 148, 126, 114, 98, 84

IR (KBr) 2970, 2940, 2880, 1467, 1383, 1160, 1010, 954, 915, 840, 695cm⁻¹

NMR (CDCl₃) δ 0.97 (t, 3H, J=7.4 Hz), 1.25-1.92 (m, 6H), 2.80-3.20 (m,2H), 3.34-3.46 (m, 0.45H, cis), 3.56-3.68 (m, 0.55H, trans), 4.02 (dd,0.55H, J=7.7, 8.1 Hz, trans), 4.52 (d, 0.90H, J=7.1 Hz, cis), 4.78 (dd,0.55H, J=7.1, 8.1 Hz, trans) ppm (The number of protons for the signalof each of the cis and trans forms is expressed such that the totalnumber for the cis and trans forms becomes 1.)

Specific rotation: [α]_(D) ²⁰−89.00° (CHCl₃, c=1.208)

Example 8 Synthesis of (S)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide

N-Methylmorpholine (27.3 mL) was added to a solution of(S)—N-propylnorvalinol (11.5 g) in dichloromethane (200 mL) understirring at room temperature. A solution of thionyl chloride (9.32 mL)in dichloromethane (64 mL) was added dropwise to the resulting lightyellow solution under ice-cooling and stirring. The resulting suspensionwas stirred at room temperature. Water was added to the suspension underice-cooling and stirring, and the mixture was extracted withdichloromethane. The organic layer was washed with an aqueous 1 mol/Lhydrochloric acid solution and subsequently with a saturated aqueoussodium hydrogen carbonate solution, dried over anhydrous magnesiumsulfate, and then the solvent was removed by distillation under reducedpressure. The residue was dried under reduced pressure at roomtemperature overnight to give (S)-3,4-dipropyl-1,2,3-oxathiazolidine2-oxide as a colorless oil (16.1 g, 79% yield, cis:trans=about 38:62determined from the integration ratio in ¹H-NMR).

NMR (CDCl₃) δ 0.85-1.10 (m, 6H), 1.25-1.85 (m, 6H), 2.80-3.19 (m, 2H),3.36-3.44 (m, 0.38H, cis), 3.55-3.66 (m, 0.62H, trans), 4.03 (dd, 0.62H,J=7.4, 8.1 Hz, trans), 4.52 (d, 0.76H, J=7.4 Hz, cis), 4.76 (dd, 0.62H,J=7.1, 8.1 Hz, trans) ppm (The number of protons for the signal of eachof the cis and trans forms is expressed such that the total number forthe cis and trans forms becomes 1.)

Example 9 Synthesis of (R)-3,4-dipropyl-1,2,3-oxathiazolidine2,2-dioxide

Ruthenium trichloride hydrate (10 mg) was added to a solution of(R)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide (11.09 g) in ethylacetate (58 mL) under stirring at 3° C. A cold saturated aqueous sodiumperiodate solution (200 mL) was added to the solution. The resultingsuspension was stirred under ice-cooling for 10 minutes and then furtherstirred at room temperature for 1 hour. The suspension was filtered, andthe insoluble matter was washed twice with ethyl acetate (15 mL). Thefiltrate and the washings were combined. The organic layer wasseparated, washed with a saturated aqueous sodium hydrogen carbonatesolution (15 mL), dried over anhydrous sodium sulfate and thenconcentrated under reduced pressure. Tetrahydrofuran (13.5 mL) was addedto the residue, and the mixture was concentrated under reduced pressure.The concentration was repeated three times.(R)-3,4-Dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (11.22 g, 93% yield)was obtained as a brown oil.

MS (m/z) 206, 178, 164, 136, 122, 112, 94, 85, 70, 69

IR (KBr) 2980, 2950, 2890, 1472, 1347, 1271, 1186, 1115, 1056, 974, 920,895, 813, 720, 662 cm⁻¹

NMR (CDCl₃) δ 0.98 (t, 3H, J=7.4 Hz), 0.98 (t, 3H, J=7.4 Hz), 1.24-1.44(m, 2H), 1.50-1.85 (m, 4H), 2.88-3.10 (m, 1H), 3.12-3.24 (m, 1H),3.53-3.65 (m, 1H), 4.17 (dd, 1H, J=7.1, 8.4 Hz), 4.54 (dd, 1H, J=6.4,8.4 Hz) ppm

Specific rotation: [α]_(D) ²⁰−57.65° (CHCl₃, c=1.284)

Example 10 Synthesis of (S)-3,4-dipropyl-1,2,3-oxathiazolidine2,2-dioxide

(S)-3,4-Dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (17.0 g, 98% yield)was obtained as a colorless oil, following the procedure of Example 9,but using (S)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide (16.1 g),ruthenium trichloride hydrate (20 mg) and sodium periodate (21.5 g).

MS (m/z) 207, 178, 164, 136, 122, 85, 69

IR (KBr) 2966, 2937, 2877, 1468, 1342, 1267, 1186, 1113, 1011, 972, 810,719, 629 cm⁻¹

NMR (CDCl₃) δ 0.98 (t, 3H, J=7.4 Hz), 0.98 (t, 3H, J=7.1 Hz), 1.23-1.43(m, 2H), 1.50-1.88 (m, 4H), 2.88-3.00 (m, 1H), 3.12-3.23 (m, 1H),3.54-3.65 (m, 1H), 4.17 (dd, 1H, J=7.1, 8.4 Hz), 4.54 (dd, 1H, J=6.7,8.4 Hz) ppm

Specific rotation: [α]_(D) ²⁰+58.28° (CHCl₃, c=1.098)

Example 11 Synthesis of (S)-3,4-dipropyl-1,2,3-oxathiazolidine2,2-dioxide

Ruthenium dioxide hydrate (3 mg) and a phosphate buffer solution (pH7.4, 28.7 mL) were subsequently added to a solution of(S)-3,4-dipropyl-1,2,3-oxathiazolidine 2-oxide (5.74 g) in ethyl acetate(46 mL) under ice-cooling and stirring. Sodium periodate (7.06 g) wasadded to the solution under ice-cooling and stirring, and thenvigorously stirred at room temperature for 30 minutes. The suspensionwas filtered, and the insoluble matter was washed with ethyl acetate (17mL). The filtrate and the washings were combined. The organic layer wasseparated and washed subsequently with a saturated aqueous sodiumhydrogen carbonate solution (11.5 mL), an aqueous 10% sodium thiosulfatesolution (11.5 mL) and a saturated aqueous sodium chloride solution(11.5 mL). Anhydrous sodium sulfate and activated carbon (0.57 g) wereadded to the organic layer and stirred at room temperature for 1 hour.The suspension was filtered, and the filtrate was concentrated underreduced pressure. The residue was added with tetrahydrofuran (8.6 mL)and concentrated under reduced pressure at 40° C. or lower to give(S)-3,4-dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (5.83 g, 94% yield)as an orange-brown oil.

Example 12 Synthesis of (R)-1-(benzofuran-2-yl)-2-propylaminopentaneHydrochloride

Under an argon atmosphere, n-butyl lithium (a 1.57 mol/L hexanesolution, 14.3 mL) was added dropwise over 10 minutes to a solution ofbenzofuran (2.47 mL) in tetrahydrofuran (14.3 mL) under stirring at 2°C. Under stirring at 2° C., 1,2-dimethoxyethane (2.33 mL) was added tothe resulting solution and stirred at 2° C. for 30 minutes. Understirring at 2° C., a solution of (R)-3,4-dipropyl-1,2,3-oxathiazolidine2,2-dioxide (4.22 g) in tetrahydrofuran (10.2 mL) was added dropwise tothe resulting solution over 5 minutes and stirred at 2° C. for 1 hour.Water (10.2 mL) was added to the solution under stirring at 3° C. Thesolution was stirred under ice-cooling for 15 minutes and then anaqueous layer was separated. The organic layer was extracted with water(10.2 mL) again. The aqueous layers were combined and washed withtoluene (10.2 mL). An aqueous 10 mol/L hydrochloric acid solution (8.2mL) was added to the aqueous layer under stirring at 2° C. The resultingsuspension was stirred under ice-cooling for 5 minutes and then stirredat room temperature for 2 hours. After the suspension was stirred at 2°C. for 1 hour, the precipitated crystals were collected by filtration.The resulting crystals were suspended in diisopropyl ether (20.4 mL) andvigorously stirred at room temperature for 30 minutes. The crystals wereseparated by filtration and washed with diisopropyl ether (10.2 mL). Thecrystals were suspended in diisopropyl ether (40.8 mL), and understirring at room temperature, a 1 mol/L sodium hydroxide solution (25mL) was added thereto. The resulting two-layer solution was vigorouslystirred at room temperature for about 1 hour so that the crystals weredissolved. The two-layer solution was allowed to separate. The organiclayer was dried over anhydrous sodium sulfate and then filtered, and thesodium sulfate was washed twice with diisopropyl ether (5.1 mL).Saturated hydrogen chloride in diethyl ether (10.2 mL) was added to thesolution under stirring at 2° C. and then stirred under ice-cooling for15 minutes. The precipitated crystals were collected by filtration andwashed twice with diisopropyl ether (20.4 mL). The crystal (4.40 g) wassuspended in 2-propanol (44 mL) and dissolved by refluxing and stirring.The solution was allowed to stand at room temperature for 17 hours. Theprecipitated crystals were collected by filtration and washed with colddiisopropyl ether (3° C., 11 mL twice) to give(R)-1-(benzofuran-2-yl)-2-propylaminopentane hydrochloride (2.97 g, 52%yield) as white needles.

Melting point: 165-167° C.

MS (m/z) 244, 114, 72

IR (KBr) 2950, 2850, 2775, 2710, 2675, 2505, 2440, 1600, 1465, 1448,1377, 1318, 1248, 1200, 1172, 1120, 1105, 1080, 1022, 1003, 944, 920,876, 831, 803, 770, 760 cm⁻¹

NMR (CDCl₃) δ 0.91 (t, 3H, J=7.4 Hz), 0.94 (t, 3H, J=7.4 Hz), 1.33-2.10(m, 6H), 2.77-3.05 (m, 2H), 3.27 (dd, 1H, J=9.8, 16.1 Hz), 3.40-3.68 (m,2H), 6.65 (s, 1H), 7.10-7.35 (m, 2H), 7.35-7.45 (m, 1H), 7.45-7.60 (m,1H), 9.37-9.83 (br, 2H) ppm

Elemental analysis: Calcd.: C, 68.19; H, 8.58; N, 4.97 Found: C, 68.32;H, 8.40; N, 4.87

Specific rotation: [α]_(D) ²⁰−4.23° (MeOH, c=4.400)

Optical purity: 98% ee (determined by HPLC analysis with chiral column)

Example 13 Synthesis of (S)-1-(benzofuran-2-yl)-2-propylaminopentaneHydrochloride

Under an argon atmosphere, n-butyl lithium (a 1.56 mol/L hexanesolution, 57.9 mL) was added to a solution of benzofuran (9.95 mL) intetrahydrofuran (58 mL) under ice-cooling and stirring. Underice-cooling and stirring, 1,2-dimethoxyethane (9.38 mL) was added to theresulting solution and stirred under ice-cooling for 30 minutes. Underwater-cooling and stirring, a solution of(S)-3,4-dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (17.0 g) intetrahydrofuran (40 mL) was added dropwise to the resulting solution andstirred under ice-cooling for 1 hour. Water was added to the solutionunder ice-cooling and stirring, and then an aqueous layer was separated.The organic layer was extracted with water again. The aqueous layerswere combined and washed with toluene. An aqueous 10 mol/L hydrochloricacid solution was added to the aqueous layer under ice-cooling andstirring. The resulting suspension was stirred under ice-cooling andthen stirred at room temperature for 2 hours. The suspension was againstirred under ice-cooling for 1 hour, and the precipitated crystals werecollected by filtration. The resulting crystals were recrystallized fromacetone. (S)-1-(Benzofuran-2-yl)-2-propylaminopentane hydrochloride(10.8 g, 47% yield) was obtained as colorless needles.

Melting point: 170-171° C.

MS (m/z) 246, 202, 131, 115, 72

IR (KBr) 2980, 2890, 2800, 2750, 2710, 2525, 2440, 1602, 1588, 1478,1460, 1383, 1353, 1320, 1256, 1256, 1178, 1140, 1120, 1108, 1080, 1048,1023, 1007, 953, 925, 880, 835, 805, 777, 765, 720 cm⁻¹

NMR (CDCl₃) δ 0.91 (t, 3H, J=7.4 Hz), 0.94 (t, 3H, J=7.4 Hz), 1.35-2.10(m, 6H), 2.80-3.00 (m, 2H), 3.26 (dd, 1H, J=9.4, 16.4 Hz), 3.50-3.60 (m,2H), 6.65 (s, 1H), 7.15-7.30 (m, 2H), 7.40-7.45 (m, 1H), 7.49-7.53 (m,1H), 9.35-9.70 (br, 2H) ppm

Elemental analysis: Calcd.: C, 68.19; H, 8.58; N, 4.97 Found: C, 68.31;H, 8.44; N, 4.84

Specific rotation: [α]_(D) ²⁰−4.37° (MeOH, c=4.000)

Example 14 Synthesis of (R)-1-(2-benzothienyl)-2-propylaminopentaneHydrochloride

Under an argon atmosphere, n-butyl lithium (a 1.56 mol/L hexanesolution, 44.4 mL) and 1,2-dimethoxyethane (7.2 mL) were added to asolution of benzothiophene (8.45 g) in tetrahydrofuran (120 mL) underice-cooling and stirring and then stirred under ice-cooling for 30minutes. A solution of (R)-3,4-dipropyl-1,2,3-oxathiazolidine2,2-dioxide (14.36 g) in tetrahydrofuran (43.0 mL) was added dropwise tothe resulting solution and stirred under ice-cooling for 2.5 hours.Under ice-cooling and stirring, 1 mol/L hydrochloric acid (200 mL) wasadded to the resulting solution and stirred at room temperature for 1.5hours. Diethyl ether (200 mL) was added to the solution, and the mixturewas separated. The aqueous layer was neutralized with 1 mol/L sodiumhydroxide and then extracted with diethyl ether. The organic layer waswashed with water and a saturated aqueous sodium chloride solution,dried over anhydrous sodium sulfate and then concentrated under reducedpressure. Saturated hydrogen chloride in diethyl ether (10 mL) was addedto a solution of the residue in diethyl ether (50 mL) under ice-coolingand stirring. After stirring at the same temperature for severalminutes, the solvent was removed under reduced pressure. The residue wasrecrystallized from ethanol (100 mL) to give(R)-1-(2-benzothienyl)-2-propylaminopentane hydrochloride (13.17 g, 70%yield) as white crystals.

Melting point: 192-194° C.

MS (m/z) 262, 218, 147, 114, 72

IR (KBr) 2971, 2960, 2871, 2805, 2736, 2694, 2518, 2431, 1606, 1594,1459, 1432, 1118, 836, 761 cm⁻¹

NMR (CDCl₃) δ 0.91 (t, 3H, J=7.4 Hz), 0.97 (t, 3H, J=7.4 Hz), 1.40-2.15(m, 6H), 2.80-3.05 (br, 2H), 3.30-3.50 (m, 2H), 3.65-3.85 (m, 1H), 7.22(s, 1H), 7.25-7.40 (m, 2H), 7.65-7.85 (m, 2H), 9.45-9.85 (br, 2H) ppm

Elemental analysis: Calcd.: C, 64.51; H, 8.12; N, 4.70 Found: C, 64.44;H, 7.98; N, 4.52

Specific rotation: [α]_(D) ²⁰−18.60° (CHCl₃, c=1.012)

Example 15 Synthesis of(R)-1-(3,4-methylenedioxyphenyl)-2-propylaminopentane

Under an argon atmosphere, 1,2-dimethoxyethane (7.1 mL) was added to asolution of 4-bromo-1,2-methylenedioxybenzene (8.2 mL) intetrahydrofuran (140 mL) under stirring at room temperature. Understirring at −72° C., n-butyl lithium (a 1.57 mol/L hexane solution, 86.9mL) was added dropwise to the resulting solution over 30 minutes. Theresulting suspension was stirred at −50° C. or lower for 1 hour. Understirring at −45° C., a solution of(R)-3,4-dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (14.14 g) intetrahydrofuran (34 mL) was added dropwise to the suspension over 20minutes. The solution was stirred at 10° C. or lower for 2 hours. Water(200 mL) was added to the solution under stirring at room temperature,and the mixture was separated. To the aqueous layer was addedconcentrated hydrochloric acid (22.8 mL) and then diethyl ether (70 mL)under stirring at room temperature. After vigorous stirring at roomtemperature for 2 hours, the resulting two-layer solution was separated,and the ether layer was extracted with an aqueous 1 mol/L hydrochloricacid solution (200 mL). The aqueous layer was made basic with an aqueous1 mol/L sodium hydroxide solution, and the organic layer and diethylether (100 mL) were added thereto. The organic layer was separated,washed with a saturated aqueous sodium chloride solution (30 mL), driedover anhydrous magnesium sulfate and then concentrated under reducedpressure. The residue was purified by column chromatography (NH-DM1020,AcOEt/Hexane=1/9) to give(R)-1-(3,4-methylenedioxyphenyl)-2-propylaminopentane (8.00 g, 47%yield) as a yellow oil.

NMR (CDCl₃) δ 0.85 (t, 3H, J=7.7 Hz), 0.76-1.02 (m, 3H), 1.25-1.55 (m,6H), 2.43-2.75 (m, 5H), 5.92 (s, 2H), 6.60-6.80 (m, 3H) ppm

Example 16 Synthesis of(R)-1-(3,4-methylenedioxyphenyl)-2-propylaminopentane Hydrochloride

Saturated hydrogen chloride in diethyl ether (15 mL) was added to asolution of (R)-1-(3,4-methylenedioxyphenyl)-2-propylaminopentane (8.00g) in diethyl ether (80 mL) under ice-cooling and stirring. Theprecipitated crystals were collected by filtration and washed four timeswith diethyl ether (1 mL). The resulting powder (7.44 g) was dissolvedby heating in acetone (150 mL), and the solution was concentrated toabout 100 mL. The solution was allowed to stand at 5° C. for 15 hours.The precipitated crystals were collected by filtration and washed threetimes with acetone (5 mL) to give(R)-1-(3,4-methylenedioxyphenyl)-2-propylaminopentane hydrochloride(4.58 g, 24% yield).

Melting point: 174-176° C.

MS (m/z) 250, 206, 135, 114, 72

IR (KBr) 2996, 2875, 2800, 2746, 2526, 2438, 1608, 1595, 1506, 1491,1450, 1367, 1248, 1192, 1126, 1105, 1036, 991, 930, 874, 810, 779, 758,739, 715, 642, 611, 569, 503, 422 cm⁻¹

NMR (CDCl₃) δ 0.87 (t, 3H, J=7.4 Hz), 0.97 (t, 3H, J=7.4 Hz), 1.30-1.87(m, 4H), 1.88-2.09 (m, 2H), 2.89 (dd, 1H, J=9.1, 13.5 Hz), 3.17-3.33 (m,1H), 3.37 (dd, 1H, J=5.0, 13.5 Hz), 5.95 (s, 2H), 6.74 (s, 3H),7.25-7.40 (m, 2H), 9.30-9.75 (br, 2H) ppm

Elemental analysis: Calcd.: C, 63.04; H, 8.46; N, 4.90 Found: C, 62.74;H, 8.23; N, 4.82

Specific rotation: [α]_(D) ²⁰−4.99° (MeOH, c=1.014)

Example 17 Synthesis of(R)-1-(1-triisopropylsilylindole-3-yl)-2-propylaminopentane

Under an argon atmosphere, s-butyl lithium (a 0.99 mol/Lcyclohexane/n-hexane solution, 68.7 mL) was added to a solution of2-bromo-1-triisopropylsilylindole (11.99 g) in tetrahydrofuran (85 mL)under stirring at −70° C. and then stirred at −70° C. for 30 minutes. Asolution of (R)-3,4-dipropyl-1,2,3-oxathiazolidine 2,2-dioxide (7.05 g)in tetrahydrofuran (17 mL) was added to the resulting solution understirring at −20° C. and then stirred for 13 hours, while the temperaturewas raised to room temperature. An aqueous 4 mol/L hydrochloric acidsolution (34 mL) was added to the solution under water-cooling andstirring, and then vigorously stirred at room temperature for 1 hour.The organic layer was separated, washed with a saturated aqueous sodiumhydrogen carbonate solution (30 mL), dried over anhydrous sodium sulfateand then concentrated under reduced pressure. The residue was subjectedto column chromatography (NH-DM1020, from Hexane to AcOEt/Hexane=1/7)and then further purified by column chromatography (NH-DM1020, fromAcOEt/Hexane=1/9 to AcOEt/MeOH=9/1) to give(R)-1-(1-triisopropylsilylindole-3-yl)-2-propylaminopentane (9.94 g, 73%yield) as a red oil.

MS (m/z) 400, 287, 244, 114

IR (neat) 2954, 2870, 1608, 1558, 1464, 1450, 1381, 1313, 1213, 1163,1140, 1074, 1016, 995, 962, 922, 883, 758, 739, 688, 658, 567, 519 cm⁻¹

NMR (CDCl₃) δ 0.77 (t, 3H, J=7.4 Hz), 0.93 (t, 3H, J=6.7 Hz), 1.17 (d,18H, J=7.4 Hz), 1.18-1.58 (m, 6H), 1.69 (qq, 3H, J=7.4, 7.4 Hz),2.35-2.49 (m, 1H), 2.55-2.68 (m, 1H), 2.73 (dd, 1H, J=7.7, 13.1 Hz),2.70-2.90 (m, 1H), 2.93 (dd, 1H, J=4.0, 13.1 Hz), 7.07 (s, 1H),7.09-7.19 (m, 2H), 7.44-7.53 (m, 1H), 7.55-7.63 (m, 1H) ppm

Example 18 Synthesis of (R)-1-(3-indolyl)-2-propylaminopentane

Tetra-n-butylammonium fluoride (9.64 g) was added to a solution of(R)-1-(1-triisopropylsilylindole-3-yl)-2-propylaminopentane (9.85 g) intetrahydrofuran (45 mL) under stirring at room temperature and thenstirred at room temperature for 50 minutes. A saturated aqueous sodiumhydrogen carbonate solution (20 mL) and diethyl ether (40 mL) were addedto the resulting solution. The organic layer was separated, washed witha saturated aqueous sodium hydrogen carbonate solution, dried overanhydrous sodium sulfate and then concentrated under reduced pressure.The residue was subjected to column chromatography (NH-DM1020,AcOEt/Hexane=1/6). An aqueous 1 mol/L hydrochloric acid solution (100mL) and diethyl ether (100 mL) were added to the resulting oil, and thenthe organic layer was extracted with an aqueous 1 mol/L hydrochloricacid solution. The aqueous layers were combined and washed with diethylether (30 mL). The aqueous layer was made basic with an aqueous 1 mol/Lsodium hydroxide solution and extracted twice with diethyl ether (60mL). The organic layers were combined and washed with a saturatedaqueous sodium hydrogen carbonate solution, dried over anhydrous sodiumsulfate and then concentrated under reduced pressure to give(R)-1-(3-indolyl)-2-propylaminopentane (5.78 g, 96% yield) as a lightorange oil.

NMR (CDCl₃) δ 0.81 (t, 3H, J=7.4 Hz), 0.93 (t, 3H, J=6.7 Hz), 1.25-1.65(m, 6H), 2.44-2.57 (m, 1H), 2.57-2.70 (m, 1H), 2.71-2.98 (m, 3H), 7.02(d, 1H, J=2.4 Hz), 7.11 (ddd, 1H, J=1.0, 7.7, 8.1 Hz), 7.19 (ddd, 1H,J=1.0, 7.7, 8.1 Hz), 7.36 (dd, 1H, J=1.0, 8.1 Hz), 7.62 (d, 1H, J=7.7Hz) ppm

Example 19 Synthesis of (R)-1-(3-indolyl)-2-propylaminopentanehydrochloride

Saturated hydrogen chloride in diethyl ether (20 mL) was added to asolution of (R)-1-(3-indolyl)-2-propylaminopentane (7.13 g) in diethylether under ice-cooling and stirring and then stirred at the sametemperature for 10 minutes. The precipitated crystals were collected byfiltration and washed three times with diethyl ether (10 mL). Theresulting powder (7.70 g) was suspended in acetone (20 mL), and thesuspension was stirred and refluxed for 10 minutes. The resulting yellowsuspension was filtered, and the crystals were washed with acetone (5 mLthree times) to give (R)-1-(3-indolyl)-2-propylaminopentanehydrochloride (4.43 g, 53% yield).

Melting point: 177-178° C.

MS (m/z) 245, 244, 130, 114, 72

IR (KBr) 3238, 2956, 2800, 2744, 2571, 2511, 2420, 1620, 1593, 1552,1493, 1458, 1431, 1381, 1356, 1338, 1234, 1097, 1066, 1011, 980, 931,876, 802, 748, 683, 625, 588, 565, 459, 428 cm⁻¹

NMR (CDCl₃) δ 0.82 (t, 3H, J=7.4 Hz), 0.88 (t, 3H, J=7.4 Hz), 1.40-1.70(m, 2H), 1.70-2.02 (m, 4H), 2.65-2.97 (m, 2H), 3.10-3.32 (m, 1H),3.32-3.52 (m, 2H), 7.10 (ddd, 1H, J=1.0, 7.1, 7.7 Hz), 7.119 (ddd, 1H,J=1.0, 7.1, 8.1 Hz), 7.27 (d, 1H, J=2.4 Hz), 7.39 (dd, 1H, J=1.0, 8.1Hz), 7.60 (d, 1H, J=7.7 Hz), 8.64 (s, 1H), 9.00 (br, 1H), 9.44 (br, 1H)ppm

Elemental analysis: Calcd.: C, 68.43; H, 8.97; N, 9.98 Found: C, 68.45;H, 8.80; N, 9.90

Specific rotation: [α]_(D) ²⁰−14.91° (MeOH, c=1.004)

1. A process for preparing an optically active aminopentane derivativerepresented by formula (8):

wherein Ar represents an aryl group, and * indicates the position of anasymmetric carbon atom in the R or S configuration, comprising the stepsof: i) treating an optically active oxathiazolidine derivativerepresented by formula (5-2):

wherein * indicates the position of an asymmetric carbon atom in the Ror S configuration, to react with an aryl lithium represented by formula(6):Ar—Li  (6) wherein Ar represents an aryl group, to obtain an opticallyactive lithium N-sulfonate derivative represented by formula (7):

wherein Ar and * each has the same meaning as defined above, and ii)hydrolyzing the optically active lithium N-sulfonate derivativerepresented by formula (7) to hydrolyze with an acid.
 2. The processaccording to claim 1, wherein the optically active oxathiazolidinederivative represented by formula (5-2) is obtained by treating anoptically active oxathiazolidine derivative represented by formula(5-1):

wherein * has the same meaning as defined above, with an oxidizing agentin the presence of a ruthenium catalyst.
 3. The process according toclaim 2, wherein the compound represented by formula (5-1) is obtainedby a process comprising the steps of: i) esterifying an optically activenorvaline represented by formula (1):

wherein * has the same meaning as defined above, with an alcoholpretreated with thionyl chloride to obtain an optically active norvalineester derivative represented by formula (2):

wherein R represents a lower alkyl group, and * has the same meaning asdefined above; ii) treating the optically active norvaline esterderivative of formula (2) with propionic anhydride in the presence of abase to obtain an optically active N-propionylnorvaline ester derivativerepresented by formula (3):

wherein R and * each has the same meaning as defined above; iii)treating the optically active N-propionylnorvaline ester derivative offormula (3) with a reducing agent to obtain an optically activeN-propylnorvalinol represented by formula (4):

wherein * has the same meaning as defined above; and iv) treating theoptically active N-propylnorvalinol of formula (4) with thionyl chloridein the presence of a base.
 4. The process according to any one of claims1 to 3, wherein the aryl group represented by Ar in formulae (6) to (8)is phenyl, naphthyl, benzofuryl, benzothienyl, methylenedioxyphenyl, orindolyl.
 5. The process according to any one of claims 1 to 3, whereinthe aryl group represented by Ar in formulae (6) to (8) is 2-benzofuryl.6. An optically active oxathiazolidine derivative represented by formula(5):

wherein * has the same meaning as defined above, and n represents 0or
 1. 7. A process for preparing an optically active oxathiazolidinederivative represented by formula (5-1):

wherein * has the same meaning as defined above, comprising treating anoptically active N-propylnorvalinol represented by formula (4):

wherein * has the same meaning as defined above, with thionyl chloridein the presence of a base.
 8. A process for preparing an opticallyactive oxathiazolidine derivative represented by formula (5-2):

wherein * has the same meaning as defined above, comprising treating anoptically active oxathiazolidine derivative represented by formula(5-1):

wherein * has the same meaning as defined above, with an oxidizing agentin the presence of a ruthenium catalyst.
 9. A process for preparing anoptically active oxathiazolidine derivative represented by formula(5-2):

wherein * has the same meaning as defined above, comprising the stepsof: i) esterifying an optically active norvaline represented by formula(1):

wherein * has the same meaning as defined above, with an alcoholpretreated with thionyl chloride to obtain an optically active norvalineester derivative represented by formula (2):

wherein R and * each has the same meaning as defined above; ii) treatingthe optically active norvaline ester derivative of formula (2) withpropionic anhydride in the presence of a base to obtain an opticallyactive N-propionylnorvaline ester derivative represented by formula (3):

wherein R and * each has the same meaning as defined above; iii)treating the optically active N-propionylnorvaline ester derivative offormula (3) with a reducing agent to obtain an optically activeN-propylnorvalinol represented by formula (4):

wherein * has the same meaning as defined above; iv) treating theoptically active N-propylnorvalinol of formula (4) with thionyl chloridein the presence of a base to obtain an optically active oxathiazolidinederivative represented by formula (5-1):

wherein * has the same meaning as defined above; and v) treating theoptically active oxathiazolidine derivative represented by formula (5-1)with an oxidizing agent in the presence of a ruthenium catalyst.